I'm not sure the family had time to 'hate' Anne. Her downfall was pretty quick and most of the family was scrambling to save their own necks. Mary was safely married to William Stafford and out of the line of fire so to speak. I'm also not entirely convinced Mary was 'hated'. The family had successfully, either as individuals or as a kinship network, substituted Anne for Mary in the King's attention, during Mary's second pregnancy. The family was not really 'out' much because Mary did not have significant 'livings'. Her husband, William Carey received grants during her liaison with Henry that coincided with the birth of her two children, Katherine and Henry. Their father Thomas Boleyn was elevated during this time as well. I'm not convinced they were ever 'mad' at Mary until she appeared at court pregnant by Stafford. Her marriage to Stafford was considered not a brilliant enough match for the sister of the queen of England.

Mary Boleyn was in great favor with her family because it was once believe that her beauty would gain her a fine husband. However once she was return to England, supposedly in disgrace. ( not, some books say that Mary was sent home, other say her father called her home). She was out of favor, until she became King Henry VIII mistress. Than she was the favorite. Anne became her father's favorite when caught the king attention,and later became queen.

Mary was Thomas Boleyn's (her Father's favourite child).George and Anne (siblings) got on best.It was believed Mary would marry and produce many healthy sons.Anne was sent to France when she was 12, so missed famil life. Furthermore, when Mary became Henry's mistress (when he was married to Katharine of Aragon) Mary was favoured, especially when Anne caused the King to have an accident when he visited Hever and displeased him.

I would love to know what evidence you have based your statements on. In other words, how do you know Mary was her father's favorite?

Anne was sent to the Burgundian court before she went to France. Mary was also in France. For elite children family life was not restricted to living in the parental household. It was expected, as well as a sign of loving parenting, to place children in a household of higher status as soon as reasonably possible. This was sometimes as early as 7 or 8 years old.